Grain legumes are important crops for the diversification of European farming system. In Latvia, the areas of faba beans (Vicia faba) and field peas (Pisum sativum) are increasing and legumes that have not been previously cultivated are sown. Globally, the important causal agent of legume diseases belongs to the genus Botrytis. Botrytis spp. cause significant losses in faba beans and infect a wide range of legume crops. Currently, the composition, pathogenicity and biological characteristics of Botrytis species in legumes in Latvia are not known. The aim of this study was to summarize the information about Botrytis spp. on legumes, using monographic method. The researches carried out all over the world show a high genetical diversity of Botrytis cinerea. Non-host specific B. cinerea has been found on 586 plant genera, including many legume crops. B. cinerea causes gray mold on leaves and pods of field peas, gray mold on pods of faba beans, and chocolate spot of faba bean leaves. B. fabae can infect plants from Fabaceae family. B. fabiopsis is known as a pathogen of faba beans. B. fabiopsis has been observed in Latvia, but no information is available on its presence in Europe. B. pseudocinerea has been found on beans, peas, and clover (Trifolium). Some other Botrytis spp. have been detected on legumes; however, their occurrence and importance are not clear. Summary of existing knowledge about Botrytis spp. on legumes is necessary to continue investigations about the diversity and economic importance of Botrytis spp. in legumes.

Pyrenophora tritici-repentis is a major wheat pathogen in all wheat (Triticum spp.) growing areas worldwide. Up to date, eight P. tritici-repentis races have been described based on chlorosis, necrosis, or both symptoms caused on race differential wheat genotypes: ‘Glenlea’, 6B662, 6B365, and ‘Salamouni’. Symptom development on differential genotypes depends on the interaction of the pathogen’s necrotrophic effectors named Ptr ToxA, Ptr ToxB, and Ptr ToxC with host susceptibility genes. Ptr ToxA is encoded by the single copy gene ToxA and induces necrosis on sensitive wheat cultivars. Ptr ToxB causes chlorosis and is encoded by the multicopy gene ToxB. The Ptr ToxC is the non-proteinaceous, polar, low molecular mass molecule that also induces chlorosis, but up to date, the gene encoding this toxin is unknown. Races producing Ptr ToxA are predominant in the global Ptr population. There are several reports about new putative races of P. tritici-repentis that do not conform to the current race system, so further research is required. This study aims to collect and systematise available information about the virulence and races of P. tritici-repentis.

Tan spot is an economically important disease of wheat in Latvia, but there is still insufficient information about its causal agent’s Pyrenophora tritici-repentis diversity in Latvia. The aim of this study was to evaluate the disease phenotype in the field and the possible presence of necrotrophic effectors Ptr ToxA, Ptr ToxB and Ptr ToxC in the P. tritici-repentis population in Latvia. Typical differential wheat lines ‘Glenlea’, ‘6B662’, ‘6B365’ and ‘Salamouni’ were evaluated under the field conditions in 2023 in the central part of Latvia. The highest tan spot severity was observed during the flowering stage with no significant difference between wheat genotypes. During the experiment, the typical disease phenotypes corresponding to all three known effectors were noted. Additionally, typical tan spot symptoms were determined on the resistant cultivar ‘Salamouni’, confirming the presence of new, currently uncharacterised effectors that are not compatible with the existing race model. Future studies should focus on searching for new effectors and further characterising known necrotrophic effectors, as knowledge about P. tritici-repentis and wheat interaction is still incomplete.

Japanese quince (Chaenomeles japonica) is a minor but prospective fruit crop due to the value of fruits and suitability for processing. Research aimed to clarify the incidence of quince leaf and fruit diseases depending on the year and plantation and determine the critical periods of diseases. The study was conducted from 2017 to 2019 in eight commercial Japanese quince plantations across different regions of Latvia. The incidence (%) of leaf and fruit spots and fruit rot was assessed several times during vegetation period. Considerable rot development was observed in only the first year of the study. The incidence of fruit rot in the middle of 2017 ranged from 0.7 to 11.7% depending on the plantation, while in 2018–2019 did not exceed 2% in any of the plantations. The critical period of fruit rot development was determined in the middle of fruit development and time closer to ripeness. Development of fruit spots increased closer to ripeness. In 2017, the incidence of fruit spots fluctuated from 0.7 to 44.0%, in 2018 – 7.7 to 46.0%, and in 2019 – 0.7 to 24.0%, depending on the plantation. The incidence of leaf spots reached high levels at the end of the vegetation periods (21–100% depending on year and plantation). The most critical periods of leaf spot development were the end of fruit development and full ripening of fruits. Determination of the critical periods of quince disease development could be used to create an effective and environmentally friendly disease control system.